# US 12,015,026 B2 · Methods of forming circuit-protection devices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,015,026 B2 - Document ID: US12015026B2 - Status: Granted - Kind: B2 - Application number: 17/473,285 - Filed: 2021-09-13 - Published: 2021-12-30 - Granted: 2024-06-18 - Earliest claimed: 2017-12-29 - Assignees: Micron Technology, Inc. - Applicants: Micron Technology, Inc. - Inventors: Michael A. Smith; Kenneth W. Marr - Web page: https://patentgrep.com/patent/US12015026B2 ## CPC - H10D 89/811: {using FETs as protective elements} - G11C 16/22: Safety or protection circuits preventing unauthorised or accidental access to memory cells - H10B 41/40: characterised by the peripheral circuit region - H10B 43/40: characterised by the peripheral circuit region - H10D 62/115: {Dielectric isolations, e.g. air gaps} - H10D 64/01306: {the conductor comprising a layer of silicon contacting the insulator, e.g. polysilicon} - H10D 64/01332: {Making the insulator} - H10D 84/0142: {the gate conductors having different shapes or dimensions} - H10D 84/0144: {Manufacturing their gate insulating layers} - H10D 84/0149: {Manufacturing their interconnections or electrodes, e.g. source or drain electrodes} - H10D 84/038: {using silicon technology, e.g. SiGe} - H10D 86/0214: {using temporary substrates} - H10P 52/403: {of conductive or resistive materials} - G11C 7/02: with means for avoiding parasitic signals - G11C 16/0483: {comprising cells having several storage transistors connected in series} - G11C 16/10: Programming or data input circuits - G11C 16/14: Circuits for erasing electrically, e.g. erase voltage switching circuits - G11C 16/24: Bit-line control circuits - G11C 16/26: Sensing or reading circuits; Data output circuits - H10P 50/268: {of silicon-containing layers} - H10P 50/283: {by chemical means} - H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES - G11C: STATIC STORES (semiconductor memory devices H10B) - H10B: ELECTRONIC MEMORY DEVICES - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 ## Abstract Methods of forming a circuit-protection device include forming a dielectric having a first thickness and a second thickness greater than the first thickness over a semiconductor, forming a conductor over the dielectric, and patterning the conductor to retain a portion of the conductor over a portion of the dielectric having the second thickness, and to retain substantially no portion of the conductor over a portion of the dielectric having the first thickness, wherein the retained portion of the conductor defines a control gate of a field-effect transistor of the circuit-protection device. ## Claims ### Claim 1 A method of forming a circuit-protection device, comprising: forming a dielectric having a first thickness, and having a second thickness greater than the first thickness, over a semiconductor; after forming the dielectric having the first thickness and having the second thickness, forming a conductor over and in contact with the dielectric having the first thickness and having the second thickness; and patterning the conductor to retain a portion of the conductor over a portion of the dielectric having the second thickness, and to retain substantially no portion of the conductor over a portion of the dielectric having the first thickness; wherein the retained portion of the conductor defines a control gate of a field-effect transistor of the circuit-protection device. ### Claim 2 (depends on 1) The method of claim 1, wherein patterning the conductor to retain substantially no portion of the conductor over the portion of the dielectric having the first thickness comprises patterning the conductor to retain substantially no portion of the conductor over any portion of the dielectric having the first thickness. ### Claim 3 (depends on 1) The method of claim 1, wherein forming the dielectric comprises forming portions of the dielectric at different stages of forming the circuit-protection device. ### Claim 4 (depends on 1) The method of claim 1, wherein forming the dielectric comprises forming the portion of the dielectric having the first thickness after forming at least some dielectric over a portion of the semiconductor corresponding to the portion of the dielectric having the second thickness. ### Claim 5 (depends on 1) The method of claim 1, further comprising removing the portion of the dielectric having the first thickness. ### Claim 6 (depends on 1) The method of claim 1, wherein forming the dielectric having the first thickness and having the second thickness greater than the first thickness comprises forming the dielectric to have the first thickness less than 0.8 times the second thickness. ### Claim 7 (depends on 1) The method of claim 1, wherein forming the dielectric having the first thickness and having the second thickness greater than the first thickness comprises forming the dielectric to have the first thickness less than 0.6 times the second thickness. ### Claim 8 A method of forming a circuit-protection device, comprising: forming a dielectric having a first thickness, having a second thickness greater than the first thickness, and having a third thickness greater than the second thickness, over a semiconductor; forming a conductor over the dielectric having the first thickness and having the second thickness; and patterning the conductor to retain a portion of the conductor over a portion of the dielectric having the second thickness, and to retain substantially no portion of the conductor over a portion of the dielectric having the first thickness; wherein the retained portion of the conductor defines a control gate of a field-effect transistor of the circuit-protection device; wherein forming the dielectric comprises forming the portion of the dielectric having the first thickness after forming at least some dielectric over a portion of the semiconductor corresponding to the portion of the dielectric having the second thickness; and wherein forming the dielectric further comprises forming the portion of the dielectric having the first thickness after forming at least some dielectric over a portion of the semiconductor corresponding to a portion of the dielectric having the third thickness. ### Claim 9 (depends on 8) The method of claim 8, wherein forming the dielectric having the first thickness, having the second thickness, and having the third thickness comprises forming the dielectric such that the first thickness, the second thickness and the third thickness are contiguous. ### Claim 10 A method of forming a circuit-protection device, comprising: forming a dielectric having a first thickness, and having a second thickness greater than the first thickness, over a semiconductor, wherein forming the dielectric comprises: forming a first portion of the dielectric over a first portion of the semiconductor; forming a second portion of the dielectric over the first portion of the semiconductor, and over a second portion of the semiconductor; forming a conductor over the dielectric; and patterning the conductor to retain a portion of the conductor over the first portion of the dielectric having the second thickness, and to retain substantially no portion of the conductor over a portion of the second portion of the dielectric having the first thickness; wherein the retained portion of the conductor defines a control gate of a field-effect transistor of the circuit-protection device. ### Claim 11 (depends on 10) The method of claim 10, wherein forming the first portion of the dielectric over the first portion of the semiconductor comprises exposing the semiconductor to a thermal oxidation process, and removing a portion of a resulting oxide. ### Claim 12 (depends on 11) The method of claim 11, wherein removing the portion of the resulting oxide comprises removing the portion of the resulting oxide over the second portion of the semiconductor. ### Claim 13 (depends on 11) The method of claim 11, wherein forming the second portion of the dielectric over the second portion of the semiconductor comprises exposing the semiconductor to a subsequent thermal oxidation process. ### Claim 14 (depends on 10) The method of claim 10, wherein forming the dielectric having the first thickness and having the second thickness greater than the first thickness comprises forming the dielectric such that the first thickness is less than 0.8 times the second thickness. ### Claim 15 (depends on 10) The method of claim 10, wherein forming the dielectric having the first thickness and having the second thickness greater than the first thickness comprises forming the dielectric such that the first thickness is less than 0.45 times the second thickness. ### Claim 16 A method of forming a circuit-protection device, comprising: forming a dielectric having a first thickness, having a second thickness greater than the first thickness, and having a third thickness less than the first thickness, over a semiconductor; forming a conductor over the dielectric; and patterning the conductor to retain a first portion of the conductor over a portion of the dielectric having the second thickness, to retain a second portion of the conductor over a first portion of the dielectric having the first thickness, to retain substantially no portion of the conductor over a second portion of the dielectric having the first thickness, and to retain substantially no portion of the conductor over a portion of the dielectric having the third thickness; wherein the retained first portion of the conductor defines a control gate of a first field-effect transistor of the circuit-protection device; and wherein the retained second portion of the conductor defines a control gate of a second field-effect transistor of the circuit-protection device. ### Claim 17 (depends on 16) The method of claim 16, wherein forming the dielectric comprises forming the first and second portions of the dielectric having the first thickness after forming at least some dielectric over a portion of the semiconductor corresponding to the portion of the dielectric having the second thickness, and further comprises forming the portion of the dielectric having the third thickness after forming the first and second portions of the dielectric having the first thickness. ### Claim 18 (depends on 16) The method of claim 16, wherein the dielectric comprises a first dielectric material, a second dielectric material, and a third dielectric material, and wherein forming the dielectric comprises: forming the first dielectric material over a first portion of the semiconductor corresponding to the portion of the dielectric having the second thickness; forming the second dielectric material over the first dielectric material, over a second portion of the semiconductor corresponding to the first portion of the dielectric having the first thickness, over a third portion of the semiconductor corresponding to the second portion of the dielectric having the first thickness, and over a fourth portion of the semiconductor corresponding to the portion of the dielectric having the third thickness; removing a portion of the second dielectric material that is over the fourth portion of the semiconductor; and forming the third dielectric material over the fourth portion of the semiconductor. ### Claim 19 (depends on 18) The method of claim 18, wherein forming the dielectric further comprises removing a portion of the first dielectric material extending above a surface of the semiconductor prior to forming the second dielectric material. ### Claim 20 (depends on 16) The method of claim 16, further comprising removing the second portion of the dielectric having the first thickness and the portion of the dielectric having the third thickness.